1. Field of the Invention
The present invention relates to a vehicular operation assisting system for assisting a driver in making an avoidance operation of a vehicle to avoid an obstacle.
2. Description of Related Art
There have been disclosed technological contents utilizing a steering assistance of a power steering unit to avoid an obstacle found ahead of a vehicle in its advancing direction. For instance, JP3557907A (claim 5 and others) discloses a power steering unit for assisting a driver in steering a steering wheel by an auxiliary steering torque calculated corresponding to a degree of steering torque when the driver operates the steering wheel, wherein the power steering unit calculates a predictive advancing path of own vehicle, measures temporal changes of a transverse deviation of the predictive path with respect to an obstacle, determines that the driver intents to avoid the obstacle when the transverse deviation increases and sets a control gain that increases the auxiliary steering torque.
In order to adequately assist the operation of the steering wheel by the power steering unit, it is necessary to accurately determine that the operation of the steering wheel of the driver is made to avoid the obstacle. However, it is also necessary to immediately reflect the intention of the driver wanting to avoid the obstacle to the assistance made by the power steering unit because the avoidance of the obstacle is often required in emergency.
However, there is a case when the intention of the driver may not be immediately reflected to the assistance to the avoidance operation by the technological content disclosed in JP3557907A. JP3557907A determines that the driver intents to avoid the obstacle when the transverse deviation increases. It means that when the transverse deviation does not increase, JP3557907A determines that the driver has no intention to avoid the obstacle. Suppose now a case when the obstacle is found at position having a transverse deviation in a right direction with respect to own vehicle. When the driver rotates the steering wheel left to avoid this obstacle as shown in FIG. 5 that shows a positional relationship between own vehicle and the obstacle in the prior art assistance given to an avoidance operation, it is possible to determine that the driver intents to avoid the obstacle because the transverse deviation in the right direction increases. However, the transverse deviation decreases or barely changes when the driver rotates the steering wheel right or rotates the steering wheel again right after rotating to left as shown in FIG. 6 that shows a positional relationship between own vehicle and the obstacle in another prior art assistance given to the avoidance operation. Then, determining that the driver has no intention to avoid the obstacle, the power steering unit makes no assistance to steering of the steering wheel until when the transverse deviation increases in this state.
In view of the problem described above, there is a need for providing a system that clearly reflects the intention of the driver wanting to avoid the obstacle to the assistance to the avoidance operation.